SOME RESULTS OF TECTONOMAGNETIC MONITORING IN THE EPICENTRAL ZONE OF THE M7.5 ALTAY EARTHQUAKE, SEPTEMBER 27, 2003

Abstract

We report tectonomagnetic results from the epicentral area of the 27 September 2003 Ms = 7.5 earthquake in the Altay mountains, southern West Siberia. The results were obtained in the first three survey campaigns in early October 2003, late November 2003, and latest May-early June 2004 using an array of one continuous-measurement station and fifteen repeated-survey sites. Changes in total geomagnetic field associated with seismic activity were mostly of regional scale and usually did not exceed 1.5 nT. The M =4.5 aftershock of 31 May 2004 was accompanied by an anomaly of 1-2 nT. The location of the anomaly within highly magnetic rocks can be evidence of its piezomagnetic origin.